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Use the same or different SSID name for both 2.4/5Ghz bands?

Discussion in 'General Wireless Discussion' started by ejp, Aug 16, 2014.

  1. sfx2000

    sfx2000 Part of the Furniture

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    Maybe it is picking the right band/AP - all depends on how it sees the current RF environment... In my experience, both the Nexus 5 and the Samsung GS4 generally make good choices for the experience at the app level in a common SSID network.

    Always goes to say though, every WiFi network is different...
     
  2. RMerlin

    RMerlin Part of the Furniture

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    Which means that, as an end-user, you have no way of knowing for sure if your device will be making any intelligent decision, since every manufacturer can decide on which criteria to base such a decision on. And that's in addition of those hidden settings that I mentioned where you can tell it which band to "prefer", assuming you knew where to look to find those settings.

    All the more reasons to take it into your own hands by using different SSIDs - only way to be sure that the correct decision will be taken.

    Seeing how poor of a job router drivers are doing at selecting the ideal channel when leaving things on "Auto" doesn't inspire me any confidence in their ability to make the best decision with the client either.
     
  3. azazel1024

    azazel1024 Very Senior Member

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    Except in my experience letting the client decide (in the absence of band/WAP steering from the base stations) instead of forcing a client to be on one set band is the best way to do it.

    5GHz, with the exception of open air, has less range than 2.4GHz, but almost always has better performance than 2.4GHz at short range, even in the case of uncluttered EMI environments, especially when you are looking at 20/40MHz on 2.4GHz 11n versus 40/80MHz with 11ac. However, a lot of times AP density is not such that there'll be good hand-off between the APs on the 5GHz band before 5GHz performance drops below that of 2.4GHz performance.

    Granted, I have one 11n and one 11ac base station inside my house, but with that, 2.4GHz is faster in some parts of my house than 5GHz is. If I set a unique SSID for 5GHz, my devices will NOT roam over to the 2.4GHz band when in those areas and stay with 5GHz, even though it is slower than 2.4GHz. However, with a unified SSID I DO see them roam over to 2.4GHz most of the time that 2.4GHz would be faster than 5GHz. It doesn't always happen, but it DOES happen some/most of the time. In the converse, I will say that IF one of my clients roams over to 2.4GHz, it rarely moves back to 5GHz when close to base station, I generally have to roam to the other base station before it'll decide to switch back to 5GHz.

    Exceptions, if I set the WAP to 20MHz 2.4GHz, then devices are much more likely to roam back to 5GHz after a minute or so of being close to the WAP (I have it set to 40MHz 2.4GHz and 40MHz 5GHz). Our iPhones and my wife's iPad 2 ALWAYS roam back to 5GHz given 2-5 minutes of being close to the WAP (this may be in part because I know my iPhone 5, and maybe her iPhone 4s are both 40MHz capable in 5GHz, but only 20MHz capable in 2.4GHz...no idea why the iPad 2 does it as it is only 20MHz capable in both bands).

    Of course for max performance, I keep the WAP on 40MHz 2.4 and 5GHz, because the WAP covers most of the house where I am more likely to want performance for my wireless devices. The router, though faster...is a better actual router, so it stays in the location even though it is >>>faster on 5GHz (and actually slightly faster on 2.4GHz too if I set it to 40MHz mode) than my WAP is. So it lives with 20MHz 2.4GHz and 80MHz 5GHz, so as to not overlap the channels of my WAP.

    Devices there almost always roam to 5GHz once they get close to the router even if they were on 2.4GHz before. Mostly, but not always though.

    In my front yard for both the WAP and router, devices almost exclusively connect to 2.4GHz since the 5GHz signal is so weak in comparison once you get outside of my house. I have a 2.4GHz only WAP covering my backyard, though I plan to replace it with my spare WDR3600 at some point (I want to see how the WAP fares over the winter, even though I plan to leave it unplugged through the winter as I won't really need wireless access outside from November-March, and my indoor WAP does cover my deckwith 2.4GHz, just not as great as I'd really prefer (around -68 to -76dBm depending on where I am standing on the deck)).

    Which that also goes back to the seperate SSIDs...if I had devices "stuck" on only the 5GHz, they'd have (DO have as I've tested) a heck of a time when stepping outside. Pretty much the only time they'll switch over to the 2.4GHz SSID is if the 5GHz SSID disappears, which often results in VERY non-seamless roaming as I drop the wireless connection completely a lot of times for several seconds before it'll connect to the 2.4GHz SSID, for example going outside and stepping more than a few feet from my house (that -68 to -78dBm for 2.4GHz on my back deck with the indoor WAP is -86 to zero for the 5GHz signal, front of the house is slightly better, but still around -83 to zero once I get more than about 15-20ft from the front of my house it disappears completely).

    My clients are iPad 2, iPhone 4s, iPhone 5, Asus T100, HP Envy 4t on Windows 8.1 with an Intel 7260ac in it, Asus Memo Pad HD7 (two of them, running 4.2.2 I think), which doesn't include a few other wired/wireless devices that exist as wired only (other than some testing, IE Apple TV, network printer and one or two others). In all, they all generally work extremely well with a unified SSID across bands and across WAPs/router.
     
  4. sfx2000

    sfx2000 Part of the Furniture

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    Chipsets could - if the chipset OEM's had a strong case to do so... most of them only do a scan on boot for WiFi... with the exception of 5GHz chipsets if tuned/enabled for the DFS channels, and even then, most only look for radar type signals once up and running...

    sfx

    FWIW - the Atheros 802.11 b/g chipset in my Aruba RAP2 does tend to hop around dynamically based on current RF conditions, so it's entirely possible...
     
  5. RMerlin

    RMerlin Part of the Furniture

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    Broadcom-based routers do run a daemon named acsd which does (amongst other things) handle scanning, checking for DFS, etc... I don't know however how dynamic it is, or how frequently it does its things. But the daemon keeps running in background, so I would assume it doesn't just do its scans at boot time.
     
  6. sfx2000

    sfx2000 Part of the Furniture

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    Looking at the code on your GIT - looks like boot/run time...

    Can't comment any further...

    sfx
     
  7. RMerlin

    RMerlin Part of the Furniture

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    After being started it keeps running, occasionally outputting scan progress reports on the serial console.

    Sent from my Nexus 4 using Tapatalk
     
  8. speedlever

    speedlever Regular Contributor

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    My brief trials with using a single SSID vs different SSIDs for the different bands and the repeater (is that the correct terminology for a router wired LAN to LAN to the primary router and used to extend wifi coverage?) is that a single SSID works, but not as well as using different SSIDs.

    In my home, I have coverage from end to end with the repeater... such that even a weaker signal at the far end is still strong enough to keep the connection. I've tested throughput and while I can get much better throughput with the stronger signal, the device and router keep the weaker signal connected. I guess it hasn't degraded enough to auto-switch to another, stronger SSID signal.

    Ergo, I prefer to choose my connections in this case and just manually connect to the stronger SSID signal if it is not automatically selected. I do not know how to force the connection to the stronger of the same SSID named signals.

    Edit: I believe the correct terminology I was looking for is WAP rather than repeater.
     
    Last edited: Aug 26, 2014
  9. stevech

    stevech Part of the Furniture

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    user devices vary greatly in their method to discover some/all and make a choice.

    I doubt a client can distinguish between an AP and a WDS "repeater" and a WiFi router - they are all APs from the client's perspective and they all use the same beacon. (Consumer products that is).
     
  10. azazel1024

    azazel1024 Very Senior Member

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    Correct. In my limited testing with a repeater I have, it does cause some roaming issues if I use the same SSID. I guess that is one caveat I would use with the "same SSID for all APs and bands" is that it is not the case when you are utilizing a repeater in your network.

    There I find that devices are either switching to the reapter too soon, even though they still have a good connection to the AP that the repeater is connected to, resulting in big drops in performance, or else hang on to the repeater too long once you get near the AP the repeater is connected to, again, big drops in performance.

    If it was just functioning as an access point instead of a repeater, that likely wouldn't be an issue at all and the behavior on the "far side" of the repeater away from the AP is generally pretty good, but once you get within about 10ft or so of the repeater and then closer to the access point, the performance of the client is always better connected to the access point directly than it is connected to the repeater.

    Ergo, only connect to a repeater if you are far from the access point AND repeater, and never when you are closer to the AP than the repeater or even if you are simply close to the repeater. Example connected direct to my AP standing next to my repeater I can get ~7MiB/sec 2.4GHz 20MHz, switching to the repeater my performance drops to ~4MiB/sec. If I move about 15ft and 2 walls further from the repeater, my direct AP connection drops to 2MiB/sec, but connecting to the repeater my performance is at 3.2MiB/sec.

    Move even closer to the AP than the repeater by 7-8ft and the direct AP connection is ~10MiB/sec, but to the repeater it is ~4MiB/sec still.

    So with the testing I am doing with the repeater I am leaving it as a seperate SSID from my main network and doing manual connections.
     
  11. azazel1024

    azazel1024 Very Senior Member

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    What devices are you using? If a windows device, every single wireless adapter I have ever seen has an option under the advanced driver properties to change the roaming aggressiveness. Generally setting it to the highest will ensure very good roaming. I notice no difference in power consumption when I do this on my laptop and tablet, but roaming works a lot better between my router and AP. Of the 5 settings I am presented with for both devices, the medium agressive behavior seems to be roughly how my iOS devices behave, with agressive being a little better/faster at roaming than my iOS devices. My android devices seem to be more like the middle/neutral roaming agressiveness setting. Setting roaming to low in windows basically means that my windows devices will not roam at all (effectively) between the router and AP in my house.

    In general the signal strength has to below a certain threshold for your devices to start looking for a new AP to connect to, and then the new AP has to be a certain amount stronger than the current AP. Other things like MCS (speed) rates being advertised and such forth as well as what bands are also something that the OS will take in to account when choosing when and what to connect to. Generally with Windows the most agressive roaming setting will get the network stack to start looking for a new access point around -55 to -60dBm of signal strength and the new AP only has to be 10dBm higher for it to flip. The medium setting is -70dBm and the lowest setting is -80dBm (I think in all cases the new AP only has to be 10dBm higher in signal strength, though on the lowest setting it might need to be 15-20dBm higher, not sure). Of course again, advertised speeds and bands make a difference.
     
    Last edited: Aug 26, 2014
  12. speedlever

    speedlever Regular Contributor

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    It just dawned on me that long ago, I cranked up the power from 42 nominal to 70-ish on the old WRT54G. I should probably crank that back down and see what happens.
     
  13. speedlever

    speedlever Regular Contributor

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    Sorry, forgot to reply to this.

    I have a gen 1 iPad (which does, in fact, connect to the 5GHz band... noticed that disputed on another site), a couple of N laptops, an old G laptop, an assortment of gen 4 and 5 iPods, 3x-iPhone5, Galaxy S4, PS/3, and probably some other gear I don't recall at the moment.

    I didn't realize I had that many N devices and so few G devices. Which leads to another thread I need to start. ;)
     
  14. stevech

    stevech Part of the Furniture

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    What units are those numbers. Too high for dBm.
     
  15. fistv

    fistv Senior Member

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    As I remember the default on the WRT1900AC is to name both 2 and 5 the same SSID.
     
  16. speedlever

    speedlever Regular Contributor

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    mW. Here's a SS:
    [​IMG]

    Rats. My screenshot won't post.

    Or maybe it's simply the answer to life, the universe, and everything. I'm not sure. ;)
     
  17. Roy2001

    Roy2001 Occasional Visitor

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    I found this is very annoying. If I use same SSID for 2.4G/5G bands, 2.4G signal is always better than 5G while 5G is always faster, if your devices can see it.

    So if I use the same SSID I won't get the best performance. If I choose different ID, then my iphone/ipad when I am in yard where I still have 2.4G signal but no 5G. Is there anyway to set the priority order for wifi networks to tell connect to 5G first (not based on signal strength) othersize connect to 2.4G?

    I searched online but could not find a good solution.
     
  18. RogerSC

    RogerSC Part of the Furniture

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    Those numbers are supposed to be milliwatts (mw). Last I heard, the recommendation was to set that to 0, which gives you the hardware max default.
     

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